This article describes the analysis of the polytype transformation of SiC ingot. We analyzed
the sample by Raman spectroscopy and TEM observation. The result of the analysis shows the
polytype is transformed from 4H-SiC to 6H-SiC, and then returned to 4H-SiC. We found that the
direction of the c-axis is not the same as the growth direction of the ingot. And also we found the
existence of 8H-SiC at the interface between 6H-SiC and 4H-SiC region by the selected area
diffraction pattern and confirmed it by HR-TEM observation.